docs: def _compute_stddevs(self, C, mag, rjb, imt, stddev_types):
          """
          Compute total standard deviation, equations 5 and 6, page 48.
          """
          # aleatory uncertainty
          sigma_ale_m = np.interp(mag, [5.0, 5.5, 8.0],
                                  [C['m50'], C['m55'], C['m80']])
          sigma_ale_rjb = np.interp(rjb, [5.0, 20.0], [C['r5'], C['r20']])
          sigma_ale = np.sqrt(sigma_ale_m ** 2 + sigma_ale_rjb ** 2)
  
          # epistemic uncertainty
          if imt.period < 1:
              sigma_epi = 0.36 + 0.07 * (mag - 6)
          else:
              sigma_epi = 0.34 + 0.06 * (mag - 6)
  
          sigma_total = np.sqrt(sigma_ale ** 2 + sigma_epi ** 2)
  
          stddevs = []
          for _ in stddev_types:
              stddevs.append(sigma_total)
  
          return stddevs